PS2 File System Limitations

File names must be no more than 32 bytes long (31 characters and a trailing 0x00)

File names cannot contain the following characters: '*'(0x2a), '/'(0x2f), and '?'(0x3f)

The valid ascii range for use is 0x20 - 0x7e

All file names are case sensitive

The maximum amount of files you can have in a directory is 18*

*A valid PS2 save must have an icon.sys file and at least one icon. SCEE guidelines also request a file named the same as the directory. This means a directory can contain a maximum of 15 user data files but usually a maximum of 16 can be used by omitting the file named the same as the directory.